Fluid pressure throttle control apparatus



March 20, 1951 7 A. J. BENT FLUID PRESSURE THROTTLE CONTROL APPARATUSFiled Sept. 19, 1947 21 E? L mmco gc m O IN VEN TOR. Arthur J BentATTOBAEY locomotive.

Patented Mar. 20, 1951 1 FLUID PRESSURE THROTTLE CONTROL APPARATUSArthur J. Bent, Pittsburgh, Pa., assignor to The Westinghouse Air BrakeCompany, Wilmerding, Pa., a corporation of Pennsylvania ApplicationSeptember 19, 1947, Serial No. 774,969

6 Claims.

1 This invention relates to fluid pressure control apparatus and moreparticularly to fluid pressure apparatus for controlling the positioningof a device, such as a steam locomotive throttle.

One object of the invention is the provision of an improved apparatus ofthe above type.

Another object of the invention is the provision of an improved controlapparatus embodying an operators fluid pressure control device and afluid pressure servo-motor controlled thereby for positioning a devicesuch as a throttle for a steam Another object of the invention is theprovision of an apparatus such as defined above embodying meansoperative, in case of failure of the normal supply of fluid underpressure, to control the servo-motor by other fluid pressure such assteam.

According to the above objects, the improved control apparatus isparticularly adapted for, though not limited to, use in a systememploying a first fluid, such as air, as a normal control medium, and asecond fluid, such as steam, as a working medium. Such is the .case on asteam locomotive, and it will be assumed as an example that the fluidpressure control apparatus herein described and embodying the inventionis normally air operated for controlling a steam throttle device on asteam locomotive or the like.

Other objects and advantages will be apparent from the following moredetailed description of the invention.

In the accompanying drawing; Fig. 1 is a diagrammatic view, partly inoutline and partly in section, of a control apparatus embodying the in-.vention; and Fig. 2 is a partial plan view of an operators controldevice which, in Fig. 1, is

shown in vertical outline.

, Description In the drawings, the reference numeral l designates anadjustable engine throttle valve device for controlling flow of powerfluid, such as steam, from a pipe 2 to a pipe 3. The pipe 2 may besupplied with steam from a locomotive boiler 'throttle or maximum powerposition 01 as indicated by a dot-dash line 5,

As shown in the drawing reference numeral 1 designates a fluid pressuremotor for adjusting the position of the throttle control lever 4; andthe reference numeral 2 designates an operators control valve devic(shown partly in section and partly in outline) for controlling normaloperation of the fluid pressure motor 1; reference numeral 3'-designates a fluid pressure reservoir for storing a fluid, such as air,under pressure for use in normal operation of the control apparatus;and'reference numeral 4' designates an emergency' valve device forcontrolling emergency operation of the motor I.

The fluid pressure motor I is substantially the same as that disclosedand described in the copending application of Harry C. May, Serial No.

550,691, filed August 23, 1944, now Patent No. 2,501,729, issued March28, 1950, and assigned to the assigne of the present invention, in viewof which it will be described in the present application only in suchdetail 'as required for a comprehensive understanding of the invention.

The motor I comprises a casing containing a power portion 5' and a pilotportion 6. 'The spring 15 arranged to power portion 5 comprises a doubleacting power piston 1 having a rod 8 attached thereto and extendingthrough a suitable packing gland to the outside of the casing. The outerend of the rod 8 is pivotally connected by a pin 9 to one end of a linkID the opposite end of which is pivotally connected to the end of thethrottle control lever 4.

At one side of the power piston I there is provided a control chamber Hwhich is connected by way of a control passage I2 to a chamber l3 inpilot portion 6, through which passage and chamber 13 fluid underpressure is adapted to be supplied to and released from chamber H forcontrolling positioning of power piston l, as will hereinafter bedescribed in detail. At the opposite side of piston I there is providedanother control chamber containing a control urge said piston in thedirection of chamber 1 l and to oppose its movement in the direction ofchamber I4. The chamber i4 is connected by way of a passage 10 and'pipeI1 to the operators control valve device 2' through which it is normallyvented to atmosphere, as disclosed in the aforementioned application.

In operation, when fluid under pressure is supplied to chamber H at apressure sufficient to overcome the opposing action of spring I5, withchamber [4 open to atmosphere, the piston 1 moves against action of saidspring to a position in which the force of the spring acting on one sideof said piston equals the force of the pressure of fluid acting on theopposite side. Upon a partial release of fluid pressure from chamber II,the forces are unbalanced in favor of the spring and the piston I androd 8 move in the direction of said chamber to a position in which theequality of opposite forces acting thereon is again reestablished. Uponfull release of fluid pressure in chamber H, the spring i5 re turns thepiston l and attached rod 8 to the position shown in the drawing. Thepiston i may therefore be caused to assume any position to the left ofthe position in which it is shown in the drawing by providing the properpressure of fluid in chamber H, whether said fluid be steam, air, water,or etc.

With the piston l and attached rod 2 in the position in which they areshown in the drawing, the throttle control lever d is caused to assurneits throttle cut-off or power oif position in which it also is shown. Inthe opposite extreme position of piston l and rod 8, the throttlecontrol lever l will assume its full throttle or maximum power position.Positioning of rod 8 5 intermediate its opposite extreme limits eflectscorresponding positioning of the throttle control lever 4. Therefore,the supply of steam to the -delivery pipe 3 may be adjusted as desiredby provision of proper pressure of fluid in chamber The pilot portion 5comprises a flexible diaphragm 58 subject opposingly to pressure of aspring I 9 in an atmospheric chamber at one side and pressure of fluidin a control chamber 2! at its opposite side, the pressure of fluid inchamber 2| being adapted to be controlled by the operators controldevice 2' through a control pipe 23 and a passage 22. A stem 24 issecured to the diaphragm i8 for movement therewith within a central bore24 in the casing. A supply valve 25 is slidably disposed in a springchamber 25 formed within a hollow portion of stem 24. A compressionspring 2? is disposed in chamber 26 and arranged to urge the supplyvalve 25 to a normally seated position on a hollow seat member 28attached to the end of stem 24 which end projects into chamber IS. Thearrangement is such that as stem 24 is moved in the direction of chamber!3 the hollow seat member 28 attached thereto is moved away from thevalve 25, which, as will hereinafter be pointed out, is prevented fromsuch movement, thus allowing fluid under pressure from a supply chamber29 to flow by way of registering ports, grooves and passages in thecasing and in stem 24 and through the hollow seat member 28 into thechamber 13 hence to chamber H in the power cylinder 5 for positioningpiston i and rod 8,

the supply chamber 29 being connected by Way,

of a pipe and passag 29' to the reservoir 3.

A hollow release valve seat member 30 is slidably disposed within whatmight be called an extension of the bore 2G opening out through thecasing. A release valve 3|, having a fluted stem 32 which is slidablymounted in a central bore 33 at one end of the seat member 30, isdisposed in the chamber 13. A compression spring 34 within member 353 isarranged to hold the release valve 3! in contact with a fluted stem 35which is attached to the supply valve 25 and which projects throughmember 28 into chamber 13. An adjusting screw 36 is attached by means ofscrew-threads to the opposite end of member 30 which projects outsidethe casing.

The screw 36 is urged by spring 34, acting through the member 38, intocontact with a lever 37 pin connected at its one end to a projectingcasing member 38 and at its opposite end said lever is operativelyconnected to the piston rod 8 by means of a lug 31a projecting into anannular groove-provided in said rod. The screw 36 initially is soadjusted that when the control chamber 2i is void of fluid underpressure and the diaphragm l8 and stem 24 are in the position in whichthey are shown in the drawing, due to the action of spring Hi, the seatmember 30 will be so disposed that/the release valve 31 will beunseated, with the supply valve 25 closed, in which position they areshown in the drawing.

In operation, when fluid under pressure is supplied through passage 22to increase pressure of fluid ,in the control chamber 2! in pilotportion 6, the increased pressure, acting on one side of diaphragm I8,overcomes the opposing force of control spring [9 and causes saiddiaphragm to deflect in the direction of chamber 28 to a position wherethe increase in compression of said spring will counterbalance theincreased pressure of fluid in chamber 2|. As the diaphragm i8 is thusmoved, the stem 24 attached thereto will move in the direction ofchamber 13, carrying the spring 27, supply valve 25, and release valve35 with it until said release valve seats on member 30,whereuponcontinued movement of said stem will move same out of seatingengagement with said supply valve, since the supply valve is heldagainst further movement in this direction by its engagement with thenow seated release valve 3| which, at this time, is held againstmovement by member 30, attached adjusting screw 36, the lever 31, and arelatively great reluctance to movement of the power piston 1 and rod 8.

Upon opening of the supply valve 25, fluid under pressure from the main.reservoir 3, supplied through pipe 29' to chamber 29 containing saidsupply valve will flow past said valve to chamber 13 and thence viapassage I2 to increase pressure of fluid in chamber l I at the righthand face of power piston I to move said piston I, attached rod 8,throttle control lever 4, and lever 31 in the direction of the lefthand. After movement of diaphragm IB ceases in a position correspondingto the pressure of fluid provided in chamber 2|, as above described, themovement of the lever 3'! by piston I will allow movement of the member30 and the release valve 31 seated thereon, by pressure of fluideffective in chamber l3, outwardly with said lever, and this movement ofrelease valve 3| will permit movement of the supply valve 25 by spring21 toward its seat. The supply valve will finally engage its seat at aposition of the power piston 1 corresponding to the position of saidseat as predetermined by the pressure of controlling fluid provided inthe control chamber 21 in the pilot portion. When the supply valve 25thus closes, the flow of fluid under pressure to the chamber II willstop and hence movement of the power piston i will cease in a positioncorresponding to the pressure of fluideffective in chamber 2|.

It will thus be seen that upon a certain deflection of diaphragm 18, asdetermined by the pressure of fluid in chamber 2|, the power piston willadjust the throttle control lever 4 out of its steam cut-off positionshown in Fig. 1 to supply steam to the delivery pipe 3 in an amountproportional to the pressure of fluid provided in chamber 2| in excessof an initialpressure necessary for efiecting closure of the normallyopen release valve 3|.

If the pressure of fluid in the control chamber 2| is reduced a desireddegree, the spring l9 will then move the diaphragm It in the directionof said chamber to a new position corresponding to the reduced pressure.This movement of the diaphragm 8 will carry with it the supply valve 25and attached stem 35, thus rendering the spring 34 effective to move therelease valve 3| with the supply valve and relative to member 30 rod 8,lever 4, and lever 31, in the direction of the right hand. Movement oflever 31 will move the member 30 in the direction of the unseatedrelease valve 3|. After movement of the diaphragm IS and release valve3| ceases in a position corresponding to the reduced pressure of fluidin chamber 2|, this movement of member 30 will be relative to said valveand will finally effect closure of said valve and preventfurther reelaseof fluid under pressure from the chamber 5. Movement of piston I willthen stop in a position corresponding to the reduced pressure of fluidin control chamber 2|. This movement of piston I will operate thethrottle valve device I to correspondingly reduce the amount of steamsupplied to the pipe 3, as will be apparent. Further release of fluidunder pressure from chamber 2| will cause a further correspondingreduction in pressure of fluid in chamber and the piston i will move toa corresponding position, in the same manner as just described. Uponreducing the pressure of fluid in chamber 2| to substantiallyatmospheric pressure, the release valve 3| returns to itsriormallyuns'eated position inv which it is shown in the drawing. I

It will now be seen that any desired amount of steam normally may besupplied to the pipe 3 by providing fluid at the proper selectedpressure in chamber 2|, while a reduction in pressure of fluid in' saidchamber to substantially atmospheric pressure will effect the cuttingoff of the supply of steam to the delivery pipe 3.

As was a feature of the fluid pressure motor referred to in theaforementioned application, the motor embodies an. insuring valve devicecomprising a poppet valve 45 contained in a chamber 46 which is open tochamber l3 by way of a passage 41. The valve 45 has a flutedstemextending through a bore into a chamber 48 which is open to arelease chamber 42 via a passage 49, said valve being thus arranged tocontrol communication between chamber l3 and release chamber 42, as doesthe release valve 3|, but under different operating conditions, as willhereinafter be brought out. A spring 53 in chamber 46 acts on valve 45for urging it toward a seated position. The projecting end of the flutedstem 1'0 and out of seating engagement therewith. With attached to valve45 engages in chamber 48 the projecting end of a stem 5| which extendsthrough an opening in a wall separating said ton 53 there is a pressurechamber 55 which is connected to a branch of the passage I5 normallyopen to atmosphere.

The operators control valve device 2 comprises a handle 56 operativelyconnectedto self-lapping valve means (not shown) disposed in the portionof the casing shown in outline. The handle 55 is movable within a normaloperating range to positions between a throttle cut-01f position and afull throttle position corresponding to similar positions of the rod 8and throttle control lever 4 of motor and throttle valve device I. Apipe 51 connects device 2' with the reservoir 3, and in moving handle 55from throttle cutofi position toward and including full throttleposition the self -lapping valve means (not shown) connected thereto isrendered efifective to supply fluid under pressure from pipe 5? to pipe23 and thereby increase pressure of fluid in the control-chamber 2| ofmotor I from a certain minimum pressure, corresponding to throttlecut-off position, to a pressure in accordance with the degree ofmovement thereof in the direction of full throttle position, whichlatter position corresponds to a certain maximum pressure. By movementof handle 56 in the opposite direction, toward or to the throttlecut-off position, a release of fluid under pressure is. effected fromchamber 2| by way of pipe 23 to thereby adjust the pressure of fluid insaid chamber to a value in ac-' cordance with the new position of thehandle.

The operators control device further comprises valve means (not shown)operative by the handle 56, in all positions of said handle within thenormal range between throttle cut-01f and full throttle positions, tomaintain the pipe ll, hence chambers I4 and 55 via passage H5 in motoropen to atmosphere. To insure return of piston l and rod 8 to throttlecut-off position, in case of breakage of spring l5, the handle 55 may bemoved beyond throttle cut-01f position to a return insuring position tosupply fluid under pressure from pipe 51 to pipe l1, and thence tochambers l4 and 55 in fluid pressure motor. Increase in pressure offluid in chamber M will 'act on piston l to urge said piston in thedirection of chamber while increase in pressure of fluid in chamber 55will act on piston 53 to move said piston in the direction ofatmospheric chamber 52 to effect unseating of poppet valve 45 andthereby venting of fluid under pressure from chamber H by way of passagei2, chamber rest position in which position it is shown in the drawing.

In accordance with a feature of the invention the release passage 43 inmotor is connected to a pipe which is in turn connected to the emergencvalve device 4 which normally connects said pipe 89 to atmosphere,whereby release of fluid under pressure from chamber II in the motor I,either by way of the release valve 3| or poppet valve 45, as abovedescribed, will occur through said device.

The emergency valve device 4' is preferably mounted at the operatorsstation, such as in the cab of a steam locomotive, adjacent to thecontrol valvedevice 2. The devioe 4' comprises a hollow casing 8| havingtwo axially aligned cylindrical chambers 82 and 83 formed therein by acounterbore 84 at opposite sides of a cylindrical seat member 35 whichhas a press fit with the wall of said bore. A removable cover member 85closes the lower end of the chamber 83 which chamber is constantly opento the atmosphere by way of an exhaust pipe 81 connected thereto. Thechamber 82 is constantly open by way of a choke 88 to an emergency supplpipe 89 which may be connected to the pipe 2 for supplying fluid underpressure, such as steam, to said cham-- ber from a source thereof whichis independent of reservoir 3. The seat member 85 is provided with acentral bore 99 extending longitudinally therethrough and opening at itsopposite ends into chambers 82 and 83, respectively. Intermediate itsends the bore 90 is connected to a radial casing port 9! which isconnected to the release pipe 39. A normally closed supply valve 92,preferably in the shape of a frustrated cone, is disposed in chamber 82and is adapted to cooperat with seat member 85 to control communicationbetween the chamber 82 and the bore 99 as well as to control the rate offlow of fluid under pressure thereto, as will be described. A normallyopen release valve 93, also in the shape of a frustrated cone, isdisposed in chamber 83 and is arranged to cooperate with the member 95for controlling communication between the bore 98 and said chamber, aswell as for controlling the rate of flow of fluid under pressuretherethrough. The valves 92 and 93 are oppositely arranged and rigidlyconnected one with the other by means of a rod 94, so that both may movesimultaneously. A valve stem 95 is secured to actuate the valves 92 and93. The stem 95 extends through chamber 82 and projects out through anopening in the casing. A packing nut 96 encircles stem 95 and isadjustably secured by means of screw-threads to the casing 8! in such amanner as to eifect compression of an annular packing gland 9! intosealing engagement with the stem 95 for preventing leakage of fluidunder pressure from chamber 82 past said stem. A portion of stem 95 isin screw-threaded engagement with the nut 96, so that by turning ahandle 98 attached to its outer projecting end, the stem 95 may beextended and retracted into and out of the casing for actuating valves92 and 93.

A safety valve 99 is interposed in the release pipe 89 to serve theusual purpose of relieving an excess pressure which might build up insaid pipe, to thereby prevent damage to the motor I.

Cut-out cocks I90 and I IJI are interposed in pipes 51 and 29',respectively. Normally the cocks I99 and IIJI are open to permit controlof the fluid pressure motor I by fluid under pressure supplied fromreservoir 3 by operation of the operators control device 2'. In theevent of failure of pressure of fluid within the system, either or both,depending upon the nature of such failure, of the cut-out cocks I09 andIOI may be moved to a closed position to isolate reservoir 3 from thecontrol system.

Now assume that the handle 59 of the operators control valve device 2 ispositioned within its normal operating range and is maintaining acertain pressure of fluid in control chamber 2| of pilot portion 6 influid pressure motor I which in turn in response thereto is holding acertain pressure within chamber II in power portion so that the rod 8will be in an extended position in accordance with position of saidhandle of device 2'. 7

Now if the pressure of fluid supplied to the device 2' and/or to thefluid pressure motor I from reservoir 3 should fail accidentally, due tofailure of supply of fluid under pressure to said reservoir, breakage ofcontrol or supply pipes or the like; it will be appreciated that themotor I' will thereby be rendered non-controllable by the operatorscontrol valve device 2', and the parts of the fluid pressure motor Iupon leakage of fluid under pressure therefrom will return to theposition in which they are shown in the drawing. It will be recalledthat, in absence of fluid under pressure in chamber 2I of motor I, thesupply valve 25 is seated and the release valve 3I is unseated, thusopening the chamber I3 and connected chamber II in power portion 5 tothe release chamber 42 and pipe 89 by way of bore 33, ports 39 and 4|,and passage 43. With chamber II thus vented, the throttle control lever4 will assume throttle cut-off position and supply of steam from pipe 2to the locomotive driving means via pipe 3 would be cut off so that thelocomotive would not operate.

Under such an emergency situation, to efiect operation of thelocomotive, the operator or engineer, as the case may be, will turn thehandle 98 of the emergency control valve device 4 in such a direction aswill effect unseating of the supply valve 92 therein, allowing steam, orfluid under pressure from a source, independent of the reservoir 3', toflow from the pipe 89 connected to pipe 2 by way of choke 88, chamber82, bore 99, and passage 9! into the release pipe 89. The steam or otherfluid thus supplied to the pipe 89 will flow into the release passage43, and, by way of the unseated release valve 31 and open communicationpreviously defined, will flow into the chamber II in the power portion5. The pressure of the steam thus supplied to chamber I I underemergency conditions will act to operate the power piston 1 and rod 8and thereby lever 4 in the same manner as was previously described inregard to normal operation thereof by air. In this manner, thelocomotive steam throttle valve device I may be operated to bring thelocomotive controlled thereby into service.

In the emergency control valve device 4, when the valve 92 is initiallyopened, the release valve 93 attached thereto is also open, so thatsteam supplied to the bore 99 will flow through chamber 83 to theatmosphere by way of the exhaust pipe 81, as well as into the releasepipe 86 for operating the motor I. By adjustment of the shaft 95,effected by turning handle 98, the valve 92 may be positioned closer toor further away from the seat member 35 while the attached valve 99 isthus positioned conversely. The effect of moving either of the conicalshaped valves away from seat member is to increase the flow area pastthe respective unseated valve, and the effect of moving either of saidvalves toward said seat member is just the opposite, that is, todecrease the flow area past the valve. The flow area past valve 92'determines the rate of flow of steam from chamber 32 into bore 99, andthe flow area past valve 93 determines the rate of flow of said steam tothe atmosphere. By proper adjustment of these flow areas, as eifected bysimultaneous movement of the two valves, the pressure of steam obtainedin pipe 89 and thence chamber II in motor I may be controlled. The choke88 acts to restrict the supply of steam into the chamber 82 to preventan excessive loss of steam to atmosphere upon initially unseating valve92. It will be seen that pressure of steam supplied to chamber II inmotor I will be at a maximum when,

simultaneously, the supply valve 92 is fully open and the release valve93 is seated, and that conversely the pressure of steam in said chamberII will be substantially atmospheric when supply valve 92 is seated'andthe release valve 93 fully open. It will further be seen then that themotor 'I may be operated and positioned by steam supplied to chamberl|,and that the pressure of said steam may be controlled with sufficientaccuracy by the emergency valve device 4" to insure positioning of thelocomotive throttle valve device ,I and thereby control of thelocomotive.

Summary From the above description it will be seen that in case offailure of the normal supply of fluid under pressurefor controlling thethrottle n the locomotive, the throttle may still be controlled by fluidunder pressure from an independent source thereof, such as the steam ona steam locomotive, by operation of the operators emergency valve deviceso that the locomotive may still be operated so as to, for instance, bebrought in for repair.

Having now described my invention, what I claim as new and desire tosecure by Letters Patent, is:

1. In combination, two independent sources of fluid under pressure, afluid pressure adjustable motor, pilot means operable by fluid underpressure from one of said sources for supplying fluid under pressurefrom said one source to said motor and upon release of fluid underpressure to establish a fluid pressure release communication from saidmotor, an operators control device for controlling supply or fluid underpressure from said one source to said pilot means and for releasingfluid under pressure therefrom, another operators control device forselectively opening said communication to atmosphere or to the othersource of fluid under pressure, and valve means for opening and closingcommunication between said one source and the first named operatorscontrol device and said pilot means.

2. In combination, two independent sources of fluid under pressure, afluid motor comprising a fluid pressure adjustable piston subject on oneside to pressure of fluid in a first chamber and on the opposite side topressure of fluid in a second chamber, pilot means operable by fluidunder pressure from one of said sources to supply fluid under pressurefrom said one source to said first chamber and operable upon release offluid under pressure to open said first chamber to a fluid pressurerelease pipe, release ensuring means operable by fluid under pressure toconnect said first chamber to said release pipe and upon release offluid under pressure to close such connection, an operators controldevice for supplying fluid under pressure from said one source tooperate said pilot means and for simultaneously re leasing fluid underpressure from said second chamber and from said ensuring means, and foralso releasing fluid under pressure from said pilot means andsimultaneously supplying fluid under pressure from said one source tosaid second chamber and said ensuring means, and another operatorscontrol device for selectively opening said release pipe to atmosphereor to the other source of fluid under pressure.

3. In a control apparatus, the combination with a first fluid pressuresource and a second fluid pressure source, of piston means adjustable inaccordance with the degree of pressure of fluid ina chamber, fluidpressure operated valve means comprising a normally closed supply valvefor controlling supply of fluid under pressure from said first fluidpressure source to said chamber and a normally open release valve forcontrolling release of fluid under pressure from said chamber to a fluidpressure release conduit, an operators control valve device forcontrolling operation of said valve means, and an emergency valve deviceoperable to efiect supply of fluid under pressure from said second fluidpressure source to said release conduit.

4. In a control apparatus, the combination with a .flrst fluid pressuresource and a second fluid pressure source, of piston means adjustable inaccordance with the degree of pressure of fluid in a chamber, fluidpressure operated valve means comprising a normally closed supply valvefor controlling supply of fluid under pressure from said first fluidpressure source to said chamber and a normally open release valve forcontrolling release of fluid under pressure from said chamber to a fluidpressure release conduit, an operators control valve device forcontrolling operation of said valve means, an emergency valve deviceoperable to effect supply of fluid under pressure from said second fluidpressure source to said release conduit, said emergency valve devicecomprising a casing having a fluid pressure supply chamber formedtherein open to said second fluid pressure source and a fluid pressureexhaust chamber open to atmosphere, a valve seat member fixed withinsaid casing and having an opening extending therethrough between saidsupply chamber and said exhaust chamber, said opening being connected tosaid release conduit, a normally closed conical shaped supply valvedisposed in said supply chamber and adapted to cooperate with said seatmember for controlling communication between said supply chamber andsaid opening, a normally open conical shaped release valve disposed insaid exhaust chamber and adapted to cooperate with said seat member forcontrolling communication between said opening and said exhaust chamber,a rigid member securing one valve with the other, and a manuallyadjustable stem secured to the valves for simultaneously adjusting theirpositions relative to the seat member. i

5. In combination, a source ofcompressed air, a source of steam, a fluidpressure adjustable motor, one operators control device for selectivelysupplying compressed air from the first named source to said motor andfor opening said motor to a'fluid pressure release pipe, a secondoperators control device comprising a pair, of oppositely arranged andsimultaneously movable conical shaped valves one'for regulating flow ofsteam from said steam source to said release pipe and the other forcontrolling communication between said pipe and an exhaust pipe, meansfor moving said valves, and choke means for restricting flow of steamfrom said steam source to said one valve.

6. In combination, two independent sources of fluid under pressure, afluid pressure adjustable motor, pilot means operable by fluid underpressure from one of said sources for supplying fluid under pressurefrom said one source to said motor and upon release of fluid underpressure to establish a fluid pressure release communication from saidmotor, an operators control device for controlling supply of fluid underpressure from said one source to said pilot means and for releasingfluid under pressure therefrom, and another 11 operatqrs control devicefor selgctively op ng NI ED Q A -ES said communication to atmosphere orto the Number Name Date other sou e fluid u er es u "498,507 c1 r1 May30, 1393 528,275 Marti -1011130, 1894 AR HUR E a 585,377. Craig 'June29,1897 653,187 Smith Q July 3, 1900 7 1,338,379. Leach ,Q ADI. 27,1920. REFERENCES CITED 1,339,393 Inge Jan. 5, 1,932 The followingreferences are Qf record in the 2,110,702 Farmer' Mar. 8, 19.38

file of this patent: 10 2,418,129 Larson hn Apr.1, 1947

